COMMUNICATION BETWEEN MUSCULOCUTANEOUS and MEDIAN NERVES: a CADAVERIC STUDY Pitta Venkata Chandrika *1, Athota Vijayalaxmi Devi 2, R.Chitra 3
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International Journal of Anatomy and Research, Int J Anat Res 2019, Vol 7(2.3):6674-79. ISSN 2321-4287 Original Research Article DOI: https://dx.doi.org/10.16965/ijar.2019.201 COMMUNICATION BETWEEN MUSCULOCUTANEOUS AND MEDIAN NERVES: A CADAVERIC STUDY Pitta Venkata Chandrika *1, Athota Vijayalaxmi Devi 2, R.Chitra 3. *1 Assistant Professor, Department of Anatomy, Siddhartha Medical College (Govt.), Vijayawada, Andhra Pradesh, India. 2 Assistant Professor, Department of Anatomy, Siddhartha Medical College (Govt.), Vijayawada, Andhra Pradesh, India. 3 Professor and Head, Department of Anatomy, Siddhartha Medical College (Govt.), Vijayawada, Andhra Pradesh, India. ABSTRACT Introduction: The communication between musculocutaneous nerve and median nerve is an important anatomical variation to occur having serious implications during surgical procedures on arm if unnoticed and without prior knowledge. Materials and Methods: The present study was conducted in 80 upper limbs of 40 adult human cadavers (Female: 10 and Male: 30) in the Department of Anatomy, Siddhartha Medical College (Government), Vijayawada and the Department of Anatomy, N.R.I. Medical College, Guntur over a period of 4 years (2014 to 2018) during educational dissections. Results: The communication between musculocutaneous nerve and median nerve was observed in present study, which is classified in accordance with previous classifications described in the literature. In present study the incidence of communication between musculocutaneous nerve and median nerve is 25%. Conclusion: Prior knowledge of this communication between musculocutaneous and median nerves in the arm is important to avoid the surgical damage to the nerves and also explain unusual clinical presentation in shoulder injuries. KEY WORDS: Musculocutaneous nerve, Median nerve, Communication. Address for Correspondence: Dr P.V.Chandrika, M.D.(Anatomy), Assistant Professor, Department of Anatomy, Siddhartha Medical College (Govt.), Near Dr N.T.R.U.H.S., Gunadala, Vijayawada, Andhra Pradesh, PIN -.520 008, India Mobile no. – 99494 98970. E-Mail: [email protected] Access this Article online Journal Information Quick Response code International Journal of Anatomy and Research ICV for 2016 ISSN (E) 2321-4287 | ISSN (P) 2321-8967 90.30 https://www.ijmhr.org/ijar.htm DOI-Prefix: https://dx.doi.org/10.16965/ijar Article Information Received: 15 Apr 2019 Accepted: 20 May 2019 Peer Review: 16 Apr 2019 Published (O): 05 Jun 2019 DOI: 10.16965/ijar.2019.201 Revised: None Published (P): 05 Jun 2019 INTRODUCTION important clinical entity and have been reported The brachial plexus is a network of nerves by several investigators. The musculocutaneous located in the lower neck and axilla which is nerve is the terminal branch of lateral cord of formed by anterior primary rami of C5 to C8 and brachial plexus and it pierces the coracobrachia- T1 and supplies the chest, shoulder and upper lis muscle, supplies it before piercing. Then it limb. Variations in the formation and branching descends in between the biceps brachii and pattern of the brachial plexus constitute an brachialis muscles supplying them and descends Int J Anat Res 2019, 7(2.3):6674-79. ISSN 2321-4287 6674 Pitta Venkata Chandrika, et al., COMMUNICATION BETWEEN MUSCULOCUTANEOUS AND MEDIAN NERVES: A CADAVERIC STUDY. as lateral cutaneous nerve of forearm. two nerves was observed in 20 upper extremi- The median nerve is formed by the contribution ties. 4 cadavers show bilateral communications. from medial and lateral cords; one root from each Absence of musculocutaneous nerve was of them. It descends crossing the brachial observed in 7 upper extremities. artery from lateral to medial side without giving Table 1: Observations in the present study. any branches in the arm. Length of the Number of the Formation Musculocutaneous nerve has frequent varia- S.No Sex Communicating communicating of nerves tions associated with its connection to median nerve branches nerve. The knowledge of anatomical variations 1 M Normal 3.6cm Single of the peripheral nerves in the upper extremity 2 M Normal 4.1cm Single is extremely important as these could be inad- 3 M Normal 4.8cm Double vertently injured during surgical procedures, 4 M Normal 3.9cm Single administration of nerve blocks in axillary region 5 F Normal 3.3cm Double and also it explains the unusual clinical 6 M Normal 2.9cm Single symptoms. The present study is aimed at assessing the variations in the communications DISCUSSION between median nerve and musculocutaneous Absence of musculocutaneous nerve: Absence nerve which are of anatomical and clinical of musculocutaneous nerve was noted in seven significance. upper limbs in present study (0.88%). MATERIALS AND METHODS In the case of absence of musculocutaneous nerve all the three muscles viz; coracobrachia- The present study was conducted in 80 upper lis, biceps brachii and brachialis are supplied limbs of 40 adult human cadavers (Female: 10 by median nerve. This similarity also noted by and Male: 30) in the Department of Anatomy, Broca (1888) [1], Kerr (1918) [2], Le Minor (1992) Siddhartha Medical College, Vijayawada and the [3], Rao and Chaudhary (2000) [4], Sud and Department of Anatomy, N.R.I. Medical College, Sharma (2000) [5], Rajashree et al (2003) [6] and Chinakakani, Guntur (Dt) over a period of 4 years Saritha (2004) [7] in their studies. Incidence of (2014 to 2018) during educational dissections. this finding is 0.3 to 2.0% according to Broca All the cadavers were properly embalmed and [1], 5.14% by Kerr [2] and 3.33% according to fixed in formalin. The brachial plexus of both Priti Chaudary et al (2013) [8]. Rest of above sides were dissected carefully following described studies reported only single cases. standard procedure with particular importance to the communications between the musculo- No case of absence musculocutaneous nerve cutaneous and median nerves and the variations with innervations of coracobrachialis from observed were noted. Required ethical clearance branches of lateral cord and of Biceps brachii for the present study obtained from the Ethical by median nerve as described by Priti Chaudary committee of this institution. et al (2013) [8]. RESULTS Communications between musculocutaneous nerve and median nerve: Communications The results were categorized under the multiple between the musculocutaneous and median variables and compared with Le Minor’s obser- nerves is by far the most common and frequent vations. The variables considered in the present of all variations that are observed among the study are branches of brachial plexus. It varies between a 1. Whether the formation of two nerves were wide range of 1.4% to 63.5% (Sachdeva and normal. Singla 2011 [9]). Although the communications between the different nerves in the arm are rare, 2. Length of communicating branch. those between the musculocutaneous nerve and 3. Number of communicating branches. median nerve have been described from 19th In the present study, out of 80 dissected upper century [10]. The communication between extremities, the communication between the muscul ocutaneous nerve and median nerve Int J Anat Res 2019, 7(2.3):6674-79. ISSN 2321-4287 6675 Pitta Venkata Chandrika, et al., COMMUNICATION BETWEEN MUSCULOCUTANEOUS AND MEDIAN NERVES: A CADAVERIC STUDY. have been classified into five different types by Fig. 1a: Le Minor - Type 1 communication Le Minor (in 1992) [3], three different types by Venieratos and Anagnostopoulou (in 1998) [11] and Choi et al (in 2002) [12]. Le Minor [3] classified these communications into following five types. Type I: There are no connecting fibers between the musculocutaneous and median nerve as described in classic textbooks. The musculocu- taneous nerve pierces the coracobrachialis MN – Median nerve, MCN –Musculocutaneous nerve, muscle and innervates the coracobrachialis, the LR- Lateral root, MR- Medial root. biceps brachii and brachialis muscle. Fig. 2: Le Minor - Type 2 communication Type II: Although some fibers of the medial root of the median nerve unite with the lateral root of the median nerve and form the main trunk of median nerve, remaining medial root fibers run in the musculocutaneous nerve leaving it after a distance to join the main trunk of median nerve. Type III: The lateral root of the median nerve from the lateral cord runs in the musculocuta- neous nerve and leaves it after a distance to join the main trunk of median nerve. Type IV: The fibers of the musculocutaneous MN – Median nerve, MCN –Musculocutaneous nerve, LR- Lateral root, MR- Medial root, CB – Communicating nerve unite with the lateral root of the median branch, CBr – Coracobrachialis muscle, BB- Biceps nerve. After some distance, the musculocuta- Brachii muscle. neous nerve arises from the median nerve. Fig. 3: Le Minor - Type 4 communication Type V: The musculocutaneous nerve is absent. The fibers of the musculocutaneous nerve runs within the median nerve along its course. In this type the musculocutaneous nerve does not pierce the coracobrachialis muscle. Fig. 1: Le Minor classification of communication between musculocutaneous and median nerve (Type I to V). LF: Lateral cord; MF: Medial cord; MC: Musculocutaneous nerve; M: Median nerve; U: Ulnar nerve; CB: Coracobrachialis muscle; BB: Biceps brachii muscle; B: MN – Median nerve, MCN –Musculocutaneous nerve, Brachialis muscle. LR- Lateral root, MR- Medial root. Fig. 4A: Le Minor - Type 5 communication MN – Median nerve, LR- Lateral root, MR- Medial root, CBr – Coracobrachialis muscle,